If you saw a sunscreen that was marked ‘SPF30’ and one that was ‘SPF30+’, which do you think would be the better sunscreen? Asking yourself whether that’s a trick question, you’d be correct, strangely, it’s the SPF30.

I don’t intend to cause a panic with this statement, they’re both providing 30x more protection than unprotected skin, but the devil is in the detail. Before I go any further and to avoid confusion, I want to be clear that the ‘+’ in SPF50+ sunscreen is unrelated to the faults i’ll be discussing here, SPF50+ are the ‘superior’ sunscreens, if you see SPF50 alongside SPF50+, the ‘+’ is the better option and I’ll explain that in more detail later.

The difference between the ‘+’ and the ‘plus-less’ for SPF30 sunscreens is not in whether one offers more SPF than the other. The difference is in which has more UVA protection and is impossible for the average consumer to know, in fact, it’s counter intuitive, consumers are being encouraged to buy the inferior sunscreen by association that ‘+’ is better than ‘plus-less’, which is a little disturbing.

Realising we’re all time poor and save you some time, SPF30+ sunscreen has as low as 1/3 of the protection from UVA radiation (the radiation responsible for causing premature ageing and skin cancer) than an SPF30. Confused? Read on….

A radiation recap

To back track slightly, SPF is a measurement of protection against UVB radiation, those UV wavelengths that cause sunburn. UVA radiation are those wavelengths that cause skin pigmentation and are associated with skin cancers. The amount of sunburn protection is recognisable by the SPF value where SPF30 sunscreen will allow a person to spend 30x more time in the sun before they start to burn. The amount of UVA protection is far less obvious and is communicated by whether ‘broad-spectrum’ is claimed, generally SPF30/SPF30+ products both claim broad-spectrum.

The Requirements

All sunscreen sold in Australia are required to comply with the Australian/New Zealand Standard (AS/NZS 2604) and have been for quite some time. In 2012 there was an update to the previous standard that had been in place since 1998 and this is where the confusion began. There is no question that the 2012 standard was a leap forward, it took the maximum claimable SPF from 30+ to 50+ (actually SPF60), so doubled the maximum protection, it also took a much better approach to how UVA protection was measured and what was required to claim ‘broad-spectrum’.

How is/was UVA protection determined?

In 1998, UVA performance was being tested using a number of different methods, one of which included dissolving sunscreen in a solvent and analysing it with a spectrophotometer, a tool typically reserved for the analysis of raw materials in industry. These methods bore no similarity to how we use sunscreen, it wasn’t applied to skin and wasn’t then exposed to the sun where bad sunscreens often start to fail. The test methods used prior to 2012 were inappropriate and ultimately inaccurate.

In 2012, the test became far more advanced, sunscreen was applied to a skin like substance and then placed in a solar simulator where the sunscreen is exposed to UV radiation, simulating actual sun which can cause degradation of the sunscreen. The sunscreen was then tested using a Labsphere sunscreen analyser, the results from the Labsphere are then processed and weighted against the SPF that was measured from human testing to calculate the UVA-PF. Whilst the new test is still technically ‘in-vitro’, it uses an in-vivo test as its basis, saving having to test on people more than necessary, risking the health of the test subjects.

To claim ‘broad-spectrum’ in 2012 and beyond, a sunscreen was required to have a UVA-PF of at least one third of the claimed SPF, for an SPF30 sunscreen, it needed a UVA-PF of at least 10. The 1998 requirement didn’t use UVA-PF as the basis of figuring out whether it was broad-spectrum, this combined with the different test methods means that 1998 sunscreens may not pass 2012 requirements.

To figure out how they compare, we need to test sunscreens that comply with the 1998 requirement using the 2012 methods. The below graph illustrates how these vary. I have included SPF50+ to highlight the huge improvement in UVA-PF for SPF50+ sunscreens as compared to the old SPF30+ sunscreens.

Unfortunately, some time around 2012, a decision was made that any sunscreen already in the market that complied to the 1998 requirements could continue to be sold indefinitely. This allowance applied only to existing sunscreens that were already listed with the TGA, any new sunscreens had to comply with the 2012 requirements.

I recall a justification for this around 2012 with an expectation that market forces would result in the 1998 compliant sunscreens drifting off shelves. Unfortunately, it’s been 5 years and the Australian public continues to have access to subpar sunscreens with no end in sight, we have all been let down somewhat by the government department that was supposed to be looking out for our health and wellbeing.

From a consumer perspective, I can understand the decision from a ‘cosmetic’ standpoint, where a consumer buys a foundation with SPF30+ for example, the primary purpose of the product is as to colour the skin and not to prevent sun-damage. I can appreciate that it would be difficult and also expensive for some brands to change their range of SPF15 lipsticks to comply with the new requirement.

On the flip-side, for a ‘therapeutic’ sunscreen, where the primary purpose is to prevent sun related damage, the consumer should be provided some assurances that the sunscreen they’re buying is of the highest standard.

Are SPF30+ sunscreens bad?

Not all sunscreens are created equally, there may well be some SPF30+ sunscreens that may comply with current requirements and just haven’t been tested to confirm. Mineral sunscreen particularly could be expected to comply as minerals including Zinc Oxide or Titanium Dioxide aren’t photo-unstable, others using more advanced sunscreen filters or effective combinations of filters are also likely to be OK. Photo-instability (i.e. a sunscreen that is photo-unstable) refers to the issue of a sunscreen degrading and a loss of performance during exposure to the sun.

Sunscreens that combine Butyl Methoxydibenzoylmethane and Octyl Methoxycinnamate are notoriously photo-unstable and since 2012, formulators have been forced to find alternate combinations, if you see these on your SPF30+ sunscreen, use with caution,

Making an informed decision

Some brands will identify whether they comply with the 1998 or the 2012 requirement on the back of the pack, it is not a legal requirement to declare which standard a sunscreen was tested to, so it’s not cut and dry, but can be an easy way to know whether you’re buying the best SPF30 sunscreen. Cancer Council is one example of a brand that will include a remark on which standard the product complies.

To be clear, if the sunscreen is an SPF50+ or if it’s claiming 30 (no ‘+’) it complies to the 2012 requirement and is a better sunscreen, if its SPF30+, it’s an inferior sunscreen, if its less than SPF30, it becomes difficult, if you’re planning on spending time in the sun, let’s be honest, you shouldn’t be picking up anything less than an SPF30.

With regard to SPF50 vs SPF50+, both comply to 2012 requirements, the difference is in the SPF, where SPF50+ indicates the tested SPF is between 50-60 and SPF50+ has an SPF of more than 60.

Brands to watch out for

A review of sunscreens in supermarkets and pharmacies was undertaken to identify which brands continue to include SPF30+. Some brands may have already discontinued their SPF30+ products, however are still available via retail channels, this list is in no way exhaustive:

*Mineral based, may be OK

**Aerosol based, steer very clear

A side note, be wary when buying online, descriptions on retailer websites may refer to SPF30 when its SPF30+ and vice versa. Products are best bought when you can read the label and check the standard the sunscreen was tested and cite the physical label.

What can we do?

All we can do to protect ourselves is to be aware and make a more conscious effort when sunscreen shopping. Avoid SPF30+ sunscreen and any temptation that may go with a potentially cheaper option and tell your friends and family too, knowledge shared is knowledge gained!

Boycotting SPF30+ will help to stop brands manufacturing old and outdated sunscreens or at least go some way to force their hand to have them perform the necessary testing to comply with the 2012 standard. Continuing to buy SPF30+ only encourages the brand to keep making them.

In the SPF30+ vs SPF30 sunscreen showdown, SPF30 wins!

Edit (17/4/2018)

Following original publication, I was contacted by Skin Health, the brand managing organisation behind Cancer Council sunscreen. It was highlighted that the SPF30+ Everyday Sunscreen range had been discontinued in 2012 . Although I wasn’t able to find Cancer Council SPF30+ Everyday Sunscreen in store and had observed the newer ‘SPF30’ variants being sold, I had found that there had been many online retailers/pharmacies that gave the impression SPF30+ were still in the market as they hadn’t updated their product pages along with a Cancer Council promotion that had SPF30+ imagery being used. Skin Health are now working with retailers and pharmacies to correct this so all Everday variants are good Everyday variants.

Cancer Council continue to have one SPF30+ variant in the Repel range, but have indicated that this is earmarked to be replaced by SPF50+ soon.

There has been increasing consumer concern over the use of ‘chemicals’ in everyday products, as a consequence, there has been a surge in the number of do-it-yourself or homemade products being publicized on-line. Sunscreens are no exception to the DIY craze, but are these products all they’re cracked up to be? In short, the answer is no, they most certainly are not!

The chemicals argument

The principal reason behind the desire for homemade skin care products relates to concerns over the chemicals used in store bought products. Unfortunately, the concerns are not founded on fact, homemade products contain chemicals, although the chemicals may be natural, this does not miraculously make them any safer than mineral, synthetic or naturally derived alternatives, in fact, the opposite is often the case.

Naturally sources ingredients are complex mixtures of chemicals and can contain hundreds of discreet chemicals, those available to those at home are often food grade in nature and unrefined and not suitable for use on the skin. Some of the most toxic chemicals known are found in nature, a few examples include Ricin and Alfatoxin, most common pesticides are also natural.

Synthetic chemicals are also found in plants where they are unable to be extracted at meaningful quantities, nature identical synthetic chemicals will be manufactured. Synthetic chemicals often sound harmful merely as a consequence of their unpronounceable names, however, have been refined and considerably more pure than naturally sourced ingredients.

Sunscreens, more than just a number

When you buy an off the shelf sunscreen, you are buying assurances. Commercial sunscreens have been formulated by highly experienced and tertiary qualified development chemists and they have been designed and stringently tested to comply with regulatory standards.

In Australia, regulatory standard refers to an Australian & New Zealand Standard (AS/NZS 2604:2012) and the Sun Protection Factor (SPF) has been certified. For a high SPF, water resistant sunscreen for full body use, it will also comply with the Australian regulatory guidelines for sunscreens (ARGS). Further to this, the ingredients used are approved and deemed safe for use by the Therapeutic Goods Administration (TGA), and manufactured following principles of Good Manufacturing Practice (GMP). There is also a high likelihood that the product has been dermatologically tested to confirm skin compatibility and qualify as non-irritating and non-sensitizing (low allergenic).

As can be seen, the absorbance for the DIY sunscreen (white line) is incredibly low as compared to the store bought sunscreen (black line). Using software to interpret the absorbance profile, the estimated SPF for the DIY sunscreen is SPF5, 10 times less than the store bought sunscreen which has been certified as SPF50+.

Below is a similar comparison using store bought Invisible Zinc brand SPF50+ that contains ~26% zinc oxide which is more comparable to the DIY sunscreen with respect to active ingredient used, again, the DIY sunscreen has incredibly low absorbance in comparison.

What causes this difference?

The key differences between the DIY and store bought sunscreen are; zinc oxide, the other ingredients and the process used to manufacture the product.

The zinc oxide suspected to be used in Invisible Zinc SPF50+ sunscreens is a highly specialized UV filter grade zinc oxide that is only available to industry, these grades are purposely engineered to absorb more UVB light (sunburn protection) with greater transparency in the visible light region so as not to appear white on skin. There is likelihood that the zinc oxide is also used in combination with synthetic, pseudo UV filters that also absorb UVB light to achieve a high level of performance, these ingredients can include Butyl Octyl Salicylate, Polycrylene or Ethylhexyl Methoxycrylene.

Other ingredients helping to support the active ingredients achieve maximum UV light absorbance include those that help form a uniform film over the skin, minimizing the potential for unprotected skin, along with those that provide water resistance so the protection remains after swimming or exercise.

The process used to manufacture the products will also be vastly different, commercial sunscreens will often be produced with high energy mixers (think of a Nutribullet, but far more advanced and costing tens of thousands of dollars) that break up agglomerates of zinc oxide that would otherwise provide very little protection and distributing them evenly throughout the product, maximizing every possible ounce of protection from the UV filters.

Sunscreens are not art, they’re science

Making sunscreen at home may sound crafty, however, the end result delivers very questionable levels of protection from poor quality ingredients and techniques and ultimately have not been tested to confirm effectiveness, unlike those purchased from a retailer or pharmacy.

Your skin is no place to perform experiments that impact your health. The risk of sunburn as a result of not properly protecting your skin is absolute, the risk of skin cancer from repeated exposure is incredibly high, although will go unnoticed for many years. The risk of harm from synthetic chemicals is low, if a product causes an allergic reaction however, then its use should be discontinued and an alternative store bought product should be found.

Those that consider making their own sunscreen should understand they are attempting to make what can be considered an anti-cancer drug. Would they consider making a vaccine or a heart disease medication if the materials were more accessible?

Despite high SPF50+ sunscreens on the market that are capable of providing hours of protection from sun damage, it’s an unfortunate reality that people continue to become sun burnt while wearing sunscreen. The reasons why we’re still getting sun burnt are simple – we aren’t applying enough sunscreen to properly protect ourselves. Having done some investigation, I was incredibly surprised exactly how important applying the recommended amount of sunscreen is and that applying anything less gives an almost catastrophic reduction in protection.

Sunscreen testing and certification

Before going into detail, it’s worth noting that the sun protection factor (SPF) claimed on packaging have been certified in a laboratory under very detailed conditions relating to the amount of product applied to a surface area (for the technical people, its 2mg/cm-2). For your sunscreen to achieve the claimed SPF, it must be applied in the same manner and for the average adult, this means approximately 36grams (roughly 36mL) for a full body application. For the golfers out there; 36mL is roughly the size of a golf ball in terms of volume, for the chefs/cooks, its 1.5-2 Tablespoons. For those whom are above average in terms of weight or height, they’ll need to use more sunscreen and for those smaller than average (including children) less can be used.

Case Study

To use an example of how poorly this is communicated to consumers, I recently received a customer complaint where an individual believed that their SPF50+ sunscreen was faulty as the family were sun burnt after using the product. A detailed investigation found that product was not faulty, leaving consumer misuse as the likely cause.

To set the scene, a husband, wife and three children were holidaying in Queensland, Australia and spent the day at a water park between the hours of 9am to 5pm, using a SPF50+ sunscreen. The questionnaire completed by the parents suggests they followed the product directions and re-applied every 2 hours. An SPF50+ sunscreen should provide 10 hours of sun burn protection if used correctly, more than enough protection for the 8 hours they enjoyed the sun. The reason the family became sun burnt was revealed in the answer to the question “How much sunscreen was used?” the answer; “half a 100mL bottle”, interestingly the amount was also described by the consumer as a “liberal” application. Some fairly straightforward math here shows that 50mL used on 5 people would require ~10mL per person all day, with 4 applications, that’s ~2mL each application, does that sound like enough when we’re supposed to being using ~36mL every 2 hours?

Investigation

Some more detailed math, taking into account the surface area of average adults and children show that the family used, on average roughly 1/8th of the 36mL used to substantiate the SPF50+ claim. If we assume that having used 1/8th of the recommended amount, the protection would be 1/8th of the labelled SPF, this equates to an SPF of 7.5 (75 minutes) – insufficient protection for the 8 hours they were out in the sun. The reality however is considerably worse as physics is a cruel mistress, and doing something as simple as halving the quantity applied does more than just halve the performance because absorbance is what is referred to as ‘logarithmic’, bear with me as I attempt to explain.

The quantity of UV light that passes through a sunscreen diminishes more and more as it passes through, a visual explanation is provided below using a SPF 3 (offering 30 minutes of protection) sunscreen absorbing 66% of light and applied in 4 layers to create protection equal to that of a SPF75 sunscreen (offering 750 minutes of protection), 25x more protection than a single layer:

So what’s happening in the above diagram you may ask? The first layer absorbs 66% of the light, transmitting 34%, at this point we focus on what is being transmitted to illustrate, if the second layer transmits 34% of the 34% transmitted by the first layer, then the second layer transmits 11.56% (34% x 34%), the third layer transmits 34% of the 11.56% (11.56% x 34% = 3.93%) and so on and so forth.

The same works in reverse for a sunscreen which has been incorrectly applied as follows:

The above shows that using 1/4 (25%) of the recommended amount of SPF50+ sunscreen (offering 600 minutes of protection) creates protection equivalent to an SPF3 sunscreen (offering 30 minutes of protection). Going back to the original complaint where the consumer was found to have used 1/8th of the recommended amount, the equivalent protection is in fact less than SPF2, it was almost not worth the effort or expense applying any sunscreen!

The below graph may also help to explain the relationship between SPF and applied amount:

There have been a number of studies performed demonstrating how little sunscreen we as consumers apply and that sunscreen performance claimed is rarely achieved. I suggest that the underlying fault lies in the standards used to substantiate SPF where there is a huge difference between the amounts used to measure SPF in the laboratory and that typically used when we’re at the pool, beach or playing sport.

What does it all mean?

It is not necessarily reasonable to expect consumers to fully appreciate the amount we should be applying, we apply what feels right and what feels right is rarely the recommended amount! Logic suggests that the standards used to certify sunscreen should be updated to incorporate an amount that reflects what we use, or at least something more in-line with what we use, such that the claimed SPF is similar to that which we can expect to achieve. Having said that, the implications are that SPF50+ as the maximum claimable SPF isn’t likely to be reduced to account for a lower use amount so it really is up to the sunscreen industry to formulate product the encourages the use of more sunscreen, in the meantime however, we as consumers must learn to apply sunscreen properly.

It is simply not enough just to be wearing ‘some’ sunscreen, particularly if your intention is to be out in the sun for long periods of time, you must apply ‘a lot’ of sunscreen. If we were to think of UV radiation as a bullet with the potential to kill you, sunscreen could be thought of as a bullet proof vest and wrapping ourselves in aluminum foil is not going to stop a bullet… How much sunscreen should you apply, the answer is quite simply ‘a lot’.

I’ve always had reservations about the use of aerosol* based sunscreens since I had heard reports of people accidentally setting themselves on fire in the United States. Having seen an increased number of product performance complaints about aerosol based sunscreens, I had serious doubts about the ability for these products to achieve the claimed sun protection factor (SPF) and ability to prevent sunburn.

I have investigated the potential dangers of aerosol sunscreen using basic research and laboratory testing using an aerosol sunscreen that is currently on the market. While I don’t disagree with the convenience of the product and that it could encourage people to use sunscreen when they otherwise may not have and that there is a consumer demand for such products, the investigation show that my reservations were very much warranted. As I will now explain, while the products appear easy to use, they must be used with caution, so much so, that consumer should consider whether the ‘convenience’ of aerosol application is worth the risk associated with their use.

Flammability

As previously noted, there have been instances in the United States where people have caught on fire after applying aerosol based sunscreen products, causing serious burns. This is not surprising given the flammability of the Hydrocarbon (Butane) propellant/gas and Ethanol solvents used in these products. The dangers are clearly stated on pack in the form of a flammable goods placard and other written warnings on the dangerous and how not to use the product.

The risk remains that applying sunscreens around BBQ’s, people who are smoking and other sources of spark or naked flame can cause the product and persons wearing the product to catch on fire . The irony being while in the process of attempting to reduce the risk of sunburn we have increased the risk of an actual burn to our skin.

Asphyxiation

Asphyxiation refers to breathing in a gas/propellant with a reduced amount of oxygen in the air which lowers oxygen concentration in the blood stream, potentially leading to unconsciousness. Again, despite warnings on packs advising that sunscreens must be applied in a well-ventilated area, there is a risk that the user will apply the sunscreen in an enclosed space, potentially leading to asphyxiation and unconsciousness.

Explosion

No sunscreen should be left in a car which is in the sun (especially during summer) or exposed to direct sunlight or left anywhere where it may be exposed to temperatures over 30degC, as elevated temperatures will cause a degradation of the product and impact the claimed performance. The need to avoid high temperatures is even more important for aerosol sunscreens which are pressurized containers, as heat will cause the pressure within the can to increase and there is a risk of the aerosol explodin.

SPF testing and certification

The sun protection factor (SPF) of aerosol sunscreens aren’t tested and certified in the laboratory using the same application methods used for regular sunscreens and by us as consumers. The reason for this is one of practicality; the propellant/gas in the aerosol makes following the standard test method virtually impossible as the amount dispensed and applied to the skin cannot be accurately measured as the packaged product in its original form is so volatile, because of this, an alternative method is used. During laboratory testing, the volatile propellant/gas is removed from the aerosol can before testing starts, leaving only the liquid inside, this liquid is then tested in the same way as with a regular sunscreen. The propellant/gas accounts for around 40% of the contents of the aerosol, meaning 40% of product is lost during the application process with only 60% of the contents having the ability to reach our skin where it can provide the necessary protection.

The above is not a flaw in the test used to certify the SPF, however it does impact the products ability to achieve its stated SPF as a result of needing more sunscreen to be applied than would be thought necessary.

Following on from the above, when tested in the laboratory, the product is physically applied to human skin and ‘rubbed’ in, however the directions and the aerosol packaging require that the product be sprayed directly onto your skin. The spray application can affect the quality of the sunscreen layer that is formed and subsequently the quality of protection. The image below shows a close-up photo of the sunscreen after application using the sunscreen liquid rubbed on vs directly sprayed on from the aerosol sunscreen packaging, you can clearly see the difference in texture of the sunscreen and these differences could affect the quality of protection:

Loss during application

Because of the gas/propellant and the fine mist released during use, the amount of product that comes out of a can of aerosol sunscreen is not the same as what ends up on our skin. Most brands recommend spraying the product 10-15cm away from our skin and laboratory testing under ideal conditions (i.e. indoors – well ventilated area, no wind) using these guidelines found that only around 40% of the amount dispensed from the pack actually ends up on the skin. The loss of 60% of the product in application is now 20% above the gas/propellant loss outlined earlier where it was estimated 60% would reach the skin this additional loss is attributable to ‘overspray’. This loss in application would be worse if there were a breeze, if the area of application was small (such as a child’s arms and legs) or was being applied from a distance greater than the recommended 10-15cm.

Combining the amount of gas/propellant lost during application and the overspray, the total loss during application is significant at 60% of the amount in the aerosol, with only 40% reaching the skin where it can provide the necessary protection.

Change in pressure and amount applied

Over the life of an aerosol as the product is used, the amount of product/propellant in the can becomes less and this reduces the pressure within the aerosol. The pressure in the aerosol is responsible for the product being released during application, less pressure in the aerosol can results in the amount of product dispensed over a particular time becoming less. Some research found that the product would need to be sprayed 45% longer as the can approaches being empty to allow the same amount of product out of the can. Whilst it is reasonable for a user to take additional time to ensure proper application, given the sunscreen is transparent, it would be difficult for a person to understand that this would be necessary to ensure they achieve the claimed level of sunscreen protection (SPF).

Similarly, ambient temperatures can impact the aerosol pressure. Cooler temperatures reduce the pressure and the application amount, whilst warmer temperatures will increase the pressure and increase the application amount.

Understanding the application properties

To achieve the claimed SPF for regular sunscreen (non-aerosol), the average adult requires approximately 36g of product when being applied over the entire body, for the golfers out there; this is roughly the size of a golf ball in terms of volume, for the cooks, its 1.5-2 tablespoons. It is difficult enough for a person using a regular sunscreen lotion to understand what this means when sunscreens aren’t sold in golf balls and we don’t carry a set of measuring spoons. It’s even more difficult to comprehend when using an aerosol sunscreen and the dispensed product which is bordering on invisible!

I decided to try applying the sunscreen for myself to see how much sunscreen reaches my skin, weighing the aerosol before and after application, timing the application to get an idea of how long the process takes and applying what ‘felt’ appropriate. I spent a total of 2 minutes applying the aerosol sunscreen and calculated that roughly 35g of product was dispensed from the aerosol. Allowing for the gas/propellant and over-spray, I estimated 40% of the 35g would have reached my skin, meaning 14g of sunscreen reached my skin, which is just 35-40% of what I should be wearing to achieve the claimed level of sun protection (SPF)

So, should I use aerosol sunscreen?

Using the diagram above as a guide, an adult who would normally require 36g of product would need 90g from an aerosol sunscreen to obtain the 36g of product. The 90g required makes ~4.5 minutes of continuous spraying to achieve, 4.5 minutes spraying a flammable product which dramatically increases the likelihood of catching fire!

Below is the previous diagram showing the weight distribution during application to clarify.

This means that for the average adult applying sunscreen to their entire body, you should be getting only 2 applications from the average 175g can (2 applications x 90g = 180g, a fraction more than the 175g in the average aerosol).

Going back to my experiment where I applied 40% of the recommended amount of sunscreen onto the skin i.e. 14g of the 36g dispensed as a result of propellant/gas and over-spray, I calculated that the SPF50+ sunscreen (over 500 minutes of protection) was now only SPF5 (50 minutes of protection), less than 10% of the claimed protection.

The dramatic reduction in protection when combined with the increased risks of flammability and explosion, I know that I won’t be using aerosol based sunscreens, having said that however, aerosol sunscreens are safe to use when used correctly, so for those who prefer the convenience of using aerosols, please use this article as a guide to how best to achieve the most out of your favorite sunscreen and minimize the risk.

*Aerosol in the context of this article refers to aerosol spray/mist type packaging as distinct from other forms of aerosol, including bag-on-valve and bag-in-can where the propellant is separated from the product, as used for dispensing creams, lotions and gels which don’t have the same dangers with respect to flammability, asphyxiation, explosion, losses during application etc.

SolarD sunscreen was introduced into the Australian market in late 2014, advertised as being a technologically advanced formula that permits the particular wavelengths of ultra-violet light that your body uses to naturally produce vitamin D. The concept for this product is new and no doubt of interest to consumers with the increasing concerns over their vitamin D levels and reports that regular sunscreens prevent vitamin D production. Without suggesting that people should avoid using SolarD, I do feel that it should be used with caution and appropriate consideration for their sunscreen needs, lifestyle and the recommendation of their doctor.

Importance of vitamin D

Vitamin D, as with all vitamins are essential to our health, vitamin D helps the absorbtion of minerals including; calcium, iron, magnesium, phosphate and zinc, all of which are critical to bone health. Being deficient in vitamin D can cause rickets, osteomalacia and osteoporosis and has been linked to cancer, various auto-immune, cardiovascular disease and mental health.

The recommended daily amount (RDA) of vitamin D for adults who do not have a vitamin D deficiency is 600IU, this is equivalent to 0.0000015g (15µg).

Sources of vitamin D

There are two types of vitamin D, D2 and D3; vitamin D2 is found in mushrooms and ‘fortified foods’ such as milk, margarine and breakfast cereals where the vitamins have been artificially added. Sources of vitamin D3 include foods such as salmon and other oily fish, eggs and milk in addition to fortified foods and vitamin D supplements, vitamin D is also produced through sun exposure.

Vitamin D3 is the most potent and effective type of vitamin D with sun exposure being the most efficient means of attaining our vitamin D3.

The most concentrated dietary source of vitamin D is found in wild salmon which has up to 1000IU of vitamin D3 in every 100g. Turns out that a salmon a day could keep the vitamin D deficiency away, unfortunately, eating salmon everyday is not great for a balanced diet, which is why sun exposure is important.

Vitamin D3 and sun exposure

Producing vitamin D3 through sun exposure is a complex reaction that occurs within our skin, requiring sun light to drive the reaction, specifically the wavelengths of light between 270 and 320nm. Visible light are those wavelengths between 390-700nm, as the wavelengths of light required to produce vitamin D3 are below those of the visible, they are ‘ultra-violet’ (UV) wavelengths which we can call UV light.

The amount of vitamin D3 produced when exposing ourselves to sun light will vary considerably with the amount of exposed skin, age, height, skin color, time of day, season, longitude and altitude, from as little as a few minutes in summer, to a few hours in winter. Interestingly, the amount of vitamin D generated in the skin is limited, to the point where longer exposure to sun light will not necessarily increase our vitamin D levels, unlike the risk of skin damage and skin cancer which will increase the longer we spend in the sun.

Causes of sunburn and the vitamin D paradox

Ultra-violet B (UVB) light refers to those wavelengths of light between 280 and 315nm, Ultra-violet A (UVA) are those wavelengths between 315 and 390nm. The UVB wavelengths are most responsible for causing sunburn, but are also responsible for causing skin cancer and other sun damage, particularly premature ageing such as wrinkles and sun spots. The method used to test the sun protection factor (SPF) of a product uses sunburn as the endpoint to determine whether the product is providing protection simply because the sunburn is an indicator of sun damage that is (close to) immediately visible and easily measured.

You may now note that the wavelengths of light that are required to produce of vitamin D3 detailed above are the same as those that cause sunburn. A sunscreen that is aimed to prevent sunburn and that is promoted to permit the particular UVB light that your body uses to naturally produce vitamin D3 should be physically impossible.

A look at how Solar D works

The UV absorbtion spectrum of SolarD SPF50 sunscreen in comparison to a regular SPF50+ Sunscreen (below) shows SolarD absorbs less light in the UVB (280 – 315nm) region than a standard sunscreen, which goes to justify the claim that SolarD permits the particular UVB light that produce vitamin D3, but doesn’t necessarily support the SPF50 claim.

How does SolarD make sun protection claims if there isn’t enough UVB absorbtion to prevent sunburn?

Before I go into any further detail and to place the remainder of this article in context, I must highlight that I am not aware of SolarD’s technology or formulation so I do not know with any certainty how SolarD achieves their claims. Being involved in the development of sunscreens (as I am) and having been aware of the health issues surrounding vitamin D, I had already considered ways that a sunscreen can promote vitamin D production and protect against sunburn, they are unusual and in my mind, not necessarily in the consumers best interest.

Sunburn is only one symptom of sun exposure, it is the one we readily relate to as we see and feel it so soon after we have been in the sun, other symptoms include skin cancer and premature ageing such as wrinkles and sun spots. We often treat sunburn using after sun products containing anti-inflammatory ingredients such as aloe vera and green tea and also anaesthetics like lidocaine, but these products won’t undo the damage that has already been caused, only reduce the redness/pain we can see and feel.

A sunscreen could, in theory, have a high sun protection factor (SPF) without the need for the product to absorb a lot of UV light by treating the visible symptoms of sun exposure we know as sunburn. A product such as this would be reliant on those same anti-inflammatory ingredients used in after sun products to compensate for a reduction in UV absorbance relative to that of a normal sunscreen. The issue here is that by failing to absorb as much UV light, more damaging UV light will be allowed to pass through to the skin where damage will occur despite the sunburn having been masked by the ant-inflammatory action. We could liken this to spraining your ankle whilst on pain and anti-inflammatory medication, the damage was done, the ankle is now weak and unstable, we just can’t feel it and in no way was the damage prevented.

I am not suggesting that this is how SolarD functions, without seeing the product technology in its entirety; this is only my theory on how the product may perform and something worth being mindful of.

Vitamin D production vs sun protection

The primary purpose for any sunscreen is to minimize sun damage by absorbing the UV light and reducing the risks of sunburn, skin cancer and premature ageing when we’re out in the sun. Realizing that sunscreens have an obvious potential to alter the way vitamin D3 is formed and influence vitamin D deficiency and related diseases, we need to instill a balanced approach so that we get enough sun exposure to allow vitamin D production, but not so much as to cause sun damage.

While wearing a regular SPF50+ sunscreen in summer will slow the formation of vitamin D3, the small amount of UV light which does pass through over the period of a few hours will generate the same amount of vitamin D3 as spending a few minutes without sunscreen with the added benefit of their being less risk of damaging the skin and there have been studies that show this to be the case.

We should all use sunscreen whenever there is a risk of sunburn, if there is no risk of sunburn, there is no need to wear sunscreen, if in doubt though, your best to have sunscreen on. If you’re going to be outdoors outside peak sunburn times (early morning or late afternoon) or only for very short periods during the day, there is no need to apply sunscreen, by doing so, our bodies will be produce vitamin D3. For those who have concerns relating to premature ageing such as wrinkles and sun spints and prefer to wear sunscreen at all times, then SolarD may be a good option to minimize damage without inhibiting vitamin D too much, a lower SPF sunscreen would however have a similar effect.

For those who are planning on spending a lot of time in the sun, especially at the beach, pool or playing sport, your best to wear a 4 hour water resistant SPF50+ sunscreen for maximum protection, remembering the sunscreen will allow vitamin D3 to be formed. I stress this point because SolarD, being a 2 hour water resistant SPF50 sunscreen has 15-20% less SPF and half the water resistance of a 4 hour water resistant SPF50+ which is not going to provide the best protection.

To buy SolarD or not to buy SolarD

I don’t want to discourage people from using SolarD, it’s an interesting concept that will have a place on the market, however it does complicate the decision making process, particularly for those who believe their existing sunscreen is somehow less effective in terms of allowing vitamin D production to occur.

If you haven’t been diagnosed with a vitamin D deficiency, then your current lifestyle and existing sunscreen habits are working for you, there is no need for a product like SolarD. For those who have been diagnosed with a vitamin D deficiency, your doctor would offer the best solution with consideration for minor lifestyle changes to get more sun, using vitamin D supplements and perhaps recommend SolarD.

With the introduction of SPF50+ sunscreens into Australia in late 2012, early 2013, there had been, and continues to be, a belief by some (including some fairly reputable organizations), that there is a negligible increase in protection as compared to previous generation SPF30+ sunscreens. Given SPF is the acronym for ‘Sun Protection Factor’, logic should prevail that 50+ provides considerably better protection than 30 and it is, twice as good in fact!

The articles that have been written dismissing SPF50+ will always raise a supposed minor change in protection by referring to a “1.3% increase in protection” which is an incorrect representation of a factual figure. There is a 1.3% increase, however the increase relates to the absorbance, where SPF30 sunscreen absorbs 96.67% of UVB radiation (and plenty of UVA also), whilst SPF50 sunscreen absorbs 98.00% of UVB radiation (SPF50+ actually absorbs over 98.33%). If we presume an SPF30 sunscreen was to provide 300 minutes of protection, an SPF50 sunscreen certainly does not offer a paltry additional 3.9 minutes in the sun (300 minutes multiplied by the supposed “1.3% increase in protection”).

Absorbance is a measure of a physical property of a sunscreen, a moment in time, the missing piece of the puzzle, the piece that is used in calculating the SPF of a sunscreen, is time. Attempting to measure protection by referencing absorbance alone is like trying to measure speed by referencing distance and not accounting for time, something that would have Galileo rolling in his grave.

What is more critical for a sunscreen in terms of protection is not what the sunscreen absorbs, but what is does not, this is referred to as transmission, the amount of UV radiation that is not absorbed and has passed through the sunscreen onto the skin where it can cause damage. If an SPF50+ sunscreen transmits 1.67% (100% – the 98.33% absorbed) and an SPF30+ sunscreen transmits 3.33%, it quickly becomes obvious that the SPF50+ is transmitting half the amount of UVB radiation through and absorbing 200% more UVB radiation, that 1.3% sounds like allot now!

If the average person burns in 10 minutes, the amount of time a person can spend in the sun before becoming sun burnt (and would be considered ‘protected’) can be determined using the following simple equation:

Its worth keeping in mind that the above calculations assume the sunscreen is used appropriately, which it often isn’t and this is largely the reason why SPF50+ sunscreens are being made available, to account for improper use (I’ll discuss this more later, suffice to say, people are still getting sun burnt!).